The invention relates to a reinforcement beam for a vehicle, in particular a door reinforcement beam intended to limit intrusions into the passenger compartment in case of side impact.
In order to improve protection in case of impact, motor vehicles include beams in certain parts of their structure. These beams make it possible to transfer the energy of the impact toward parts of the structure of the vehicle in which the beams are fastened, and thus to limit intrusions into the space behind the beam. Such beams are, for example, used in the vehicle side doors, where they are commonly called side-impact reinforcement beams. In a door, a side-impact reinforcement beam extends between the front edge and the rear edge of the lining of the door, in zones preferably situated across from structural elements of the vehicle, for example the front pillar and middle pillar of the vehicle in the case of a front door. Thus, in the case of a side impact, the forces from the impact are transmitted by the side-impact reinforcement beam to the structural elements of the vehicle, namely the front pillar and the middle pillar. The drawback of these beams is that they deform essentially at the point of impact during the impact, generating significant intrusions into the passenger compartment.
In order to control the deformation of the reinforcement beam, European Pat. No. EP0510060 proposes a reinforcement beam made by extrusion, with a variable thickness in the length of the profile and a substantially rectangular section. The greatest wall thickness is located in the middle of the length of the profile; the thickest wall extends on either side and forms the impact zone. This impact zone is defined by two notches situated on the same face and substantially perpendicular to the longitudinal axis of the beam, so as to locally reduce the rigidity of the beam. Thus, in case of side impact, the beam will first bend at these notches. This design makes it possible to reduce the bending of the beam in case of impact, and therefore intrusions due to the impact. The notches are made during the extrusion of the beam by reducing the thickness of one of the walls of the beam obtained by moving an element at the extrusion head during the extrusion of the profile.
This beam is complex to produce, since it requires a special tool at the extrusion head to modify the thicknesses of the walls of the beam during the extrusion operation.